The present invention relates to a belt drive device, for example for thread-feeding arrangements of textile machines.
Belt drives of the type under consideration are known and usually include at least one driven endless belt and at least one driven shaft with which a belt pulley is coupled and from which it is uncoupled. The endless belt is guided over this pulley and has, at the same time, with said pulley in one region a form-locking connection and in one region only a friction locking connection.
A belt type of the foregoing type has been disclosed, for example in DE-PS No. 23 65 251 and DE-GM No. 74 19793. These publications disclose the arrangements in which flat drive belts are utilized, which are provided in the middle with a row of holes in which pins of the medium spike-like rim or crown, formed on the belt pulley, are engaged so as to effect a form-locking connection between the belt and the pulley whereas the peripheral edges of the flat belt lie on the smooth edge areas of the belt pulley to form a friction connection therewith. The flat belt provided with a perforated disc has the advantage which resides in that it can be formed of a belt piece by connecting two ends of the belt to each other to form the endless belt as known with the toothed belts, disclosed for example in DE-OS No. 25 31378; however the form-locking drive connection between the belt and the belt pulley which is provided with teeth over the entire width thereof is not possible. The fully toothed drive belts must be manufactured originally as endless belts and precisely adjusted to a desired length.
With the perforated belts mentioned hereinabove, in which a form-locking connection in one region and a friction connection in the other region between the belt and the pulley are provided, often, during the manufacture of such belts, bursting off of the belt from the pulley occurs whereby frequency of this occurrence increases with increased running speeds of the belt and increased area of the belt gripping surface. Study of the belts have shown that this bursting off tends to occur in only a small unavoidable extension of the belt, and the hole distribution or tooth-spacing of the belt due to this extension, no longer coincides with the spacing of corresponding form-locking projections or recesses of the belt pulley. The adjustment of the belt pulley to the movement of the slightly extended or elongated drive belt is, however, not possible because of the simultaneous friction-locking connection of the belt with the pulley.